Is fast charging fast enough?

Newer EVs have much faster DC fast charging than my 2018 LEAF. The Ioniq 5 promisses 350 kW DC fast charging speeds (source), Tesla model S can hit 250 kW (source), and even the 2023 Nissan Leaf Plus claims 100 kW (source). Lets do some analysis and see how charging stop duration goes with increasing charging speed. We find that the human factor (bathroom breaks, time to get food) is the limiting factor as charging speeds exceed 150 kW. Granted, if you are say towing something in a large electric truck, faster speeds would be needed, with perhaps a 350 kW charging speed.

The idea is to combine a rest stop for the humans, with a charging stop for the EV, just like you tend to gas up the car, and find some lunch at the same time with a gas car. You and your fellow humans traveling in the car, need a stop every 2 hours or so (source), otherwise you may not be alert enough to drive safely. With that, seems our road trip stop needs to collect enough charge to make 2 more hours of driving. Assuming 5 km/kWh consumption, a 90 km/hr speed, and a 2 hour drive to the next stop, we need to collect 36 kWh during our charging stop. Depending on your charging speed, this might only take 6 minutes, just enough time to use the washroom.

A 15 minute rest stop is recommended to keep you alert while driving (source), by that logic, charging speeds in excess of 150 kW will allow your EV to recharge the aforementioned 36 kWh. Granted, some feel a 10 minute rest stop is sufficient (source), while a meal break might take more than 30 minutes. Also, that 5km/kWh efficiency figure, while reasonable for my Leaf, Ioniq 5, Tesla’s and similarly sized cars on the freeway, something like the F150 Lightning would be more like 3 km/kWh possibly 2 km/kWh if towing something. Now using the same math, were need 90 kWh, in which case, we would need a bit more than 350 kW charging speed to stick to our 15 minute stop timeline.

Lots of factors influence the charging speed you actually wind up getting. My Nissan Leaf for example supports 50kW, assuming its my first fast charge of the day, I usually get 40-50kW up to 55%, with charging speeds tapering off to 20 kW at 90%. What matters here is the average charge speed, and how that jives with your life. On our North Bay run for example, we need to stop somewhere to get groceries for the weekend. Why not stop at Sobeys in Gravenhurst, where I can charge and shop at the same time. There is ample lunch opportunities too. Usually by the time we have enjoyed our lunch, shopped some groceries, and stopped by the LCBO, our Leaf has gone from 10% to 95%, plenty to get us to North Bay from Gravenhurst.